Rat liver fibrosis regresses better with pegylated interferon alpha2b and ursodeoxycholic acid treatments than spontaneous recovery (original) (raw)
Related papers
The American Journal of Pathology, 2003
Collagen degradation by matrix metalloproteinases is the limiting step in reversing liver fibrosis. Although collagen production in cirrhotic livers is increased, the expression and/or activity of matrix metalloproteinases could be normal, increased in early fibrosis, or decreased during advanced liver cirrhosis. Hepatic stellate cells are the main producers of collagens and matrix metalloproteinases in the liver. Therefore, we sought to investigate whether they simultaneously produce ␣1(I) collagen and matrix metalloproteinase-13 mRNAs. In this communication we show that expression of matrix metalloproteinase-13 mRNA is reciprocally modulated by tumor necrosis factor-␣ and transforming growth factor-1. When hepatic stellate cells are co-cultured with hepatocytes, matrix metalloproteinase-13 mRNA is up-regulated and ␣1(I) collagen is down-regulated. Injuring hepatocytes with galactosamine further increased matrix metalloproteinase-13 mRNA production. Confocal microscopy and differential centrifugation of co-cultured cells revealed that matrix metalloproteinase-13 is localized mainly within hepatic stellate cells. Studies performed with various hepatic stellate cell lines revealed that they are heterogeneous regarding expression of matrix metalloproteinase-13. Those with myofibroblastic phenotypes produce more type I collagen whereas those resembling freshly isolated hepatic stellate cells express matrix metalloproteinase-13. Overall , these findings strongly support the notion that ␣1(I) collagen and matrix metalloproteinase-13 mRNAs are reciprocally modulated. Liver fibrosis results from excess deposition of extracellular matrix components, mainly type I collagen that is produced by hepatic stellate cells (HSCs). 1-4 These cells can undergo a phenotypic change named activation. During activation HSCs acquire a different morphology and function, express higher levels of fibrillar collagens, and develop a contractile apparatus that includes the up-regulation of nonskeletal myosin and ␣-actin. 1-5 Although the activity of matrix metalloproteinases (MMPs) may be normal or increased 6,7 and the half-life of collagen I and III is decreased by 50%, 8 the capacity of HSCs to degrade fibrillar collagens may be hampered by two key factors: firstly, lack of access to digest collagen fibrils within thick, highly cross-linked collagen bundles; 8,9 and secondly, the up-regulation of tissue inhibitors of metalloproteinases (TIMPs) that blocks MMP activity. 10 -16 Indeed, under conditions in which TIMP-1 is overexpressed 17 or its expression up-regulated, 18,19 there is increased accumulation of collagen in the liver. Conversely, during resolution of liver fibrosis in a reversible Supported by the National Institute of Alcohol Abuse and Alcoholism (grants RO1AA09231 and RO1AA10541 to M. R., and RO1AA12196 to P. G.).
Hepatology, 1996
Liver fibrosis results from a relative imbalance between synthesis and degradation of matrix proteins. We have previously described release of the protein collagenase inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), by culture-activated human hepatic stellate cells (HSCs). In this study, we have investigated the relative expression of TIMP-1 and interstitial collagenase in culture-activated rat HSCs and rat models of liver injury and fibrosis. The complementary DNA (cDNA) for rat TIMP-1 was obtained by homology polymerase chain reaction (PCR) and sequenced. By Northern analysis using this probe, TIMP-1 messenger RNA (mRNA) expression was up-regulated with HSC activation by culture on plastic as defined by cellular expression of procollagen-1. Interstitial collagenase mRNA was expressed in early 1. Interstitial collagenase mRNA was expressed in early culture (<4 days) but became undetectable in more activated cells (7-21 days). By activity assay of serum-free cell-conditioned media, TIMP-1 was found to be released in increasingly concentrations with duration of culture on plastic. Expression of TIMP-1 interstitial collagenase, and procollagen-1 mRNAs were studied in rat models of biliary and parenchymal injury (bile duct ligation and CC14 administration) by ribonuclease protein assay. TIMP-1 mRNA expression was increased at 6, 24 hours, and 3 days after bile duct ligation and was also shown to rise in acute CC14 liver injury and remain elevated as the liver became fibrotic. TIMP-1 expression preceded procollagen-1 expression in both models. In contrasts, interstitial collagenase mRNA levels remained similar to control values throughout both models of liver injury. Total cellular RNA from hepatocytes, HSCs, and kupffer cells freshly isolated from livers after acute CC14 injury was subjected to Northern analysis. TIMP-1 transcripts were observed in nonparenchymal cells only. We suggest that increased expression of TIMP-1 relative to interstitial collagenase by HSCs may promote progression of liver fibrosis in these rat models by preventing degradation of secreted collagens.
Hepatology, 2001
The acute-phase response (APR) represents a systemic reaction of the organism to multiple nonspecific inflammatory stimuli. In general, it is protective for the host, and hepatocytes are the main cells responding with alterations in the expression of a set of liver-specific proteins named the acute-phase proteins. We have previously shown that although a turpentine-induced APR is not fibrogenic per se, it enhances collagen deposition in rats treated with CCl 4 and up-regulates expression of hepatic ␣1(I) collagen and tissue inhibitor of metalloproteinases 1 (TIMP-1) messenger RNAs (mRNAs). In this report we extended our studies and showed that turpentine induced, in a time-dependent manner, expression of ␣1(I) and ␣1(IV) collagens, TIMP-1, and matrix-metalloproteinase 2 (MMP-2) mRNAs. We further showed that expression of these mRNAs occurs in hepatic stellate cells, but not in hepatocytes obtained 6 hours after the induction of an APR episode. These changes were accompanied by increased blood levels of tumor necrosis factor ␣ (TNF-␣) and interleukin 6 (IL-6) without noticeable immediate changes in the expression of their respective mR-NAs in the liver. In contrast to CCl 4 -induced liver damage, turpentine alone, whether administered as a single dose or as a weekly dose for 3 weeks did not up-regulate expression of transforming growth factor 1 (TGF-1) mRNA and did not result in excess collagen deposition. Overall, these find-ings suggest that collagen deposition in the livers of rats with repeated APR episodes may be enhanced only when given together with a fibrogenic stimulus that activates hepatic stellate cells (HSCs) and/or up-regulates TGF-1 mRNA expression. (HEPATOLOGY 2001;33:597-607.) Abbreviations: APR, acute phase response; TNF-␣, tumor necrosis factor ␣; IL-6, interleukin-6; HSC, hepatic stellate cell; mRNA, messenger RNA; TIMP-1, tissue inhibitor of metalloproteinases 1; MMP, matrix metalloproteinase; TGF-1, transforming growth factor 1; cDNA, complementary DNA; GAPDH, glyceraldehyde-3-phosphatedehydrogenase; RT-PCR, reverse transcription-polymerase chain reaction.
Liver Fibrosis: Underlying Mechanisms and Innovative Therapeutic Approach. A Review Article
Biomedical and Pharmacology Journal, 2021
Liver fibrosis is considered: “a pathological repairing process in liver injuries leading to extracellular cell matrix (ECM) accumulation evidencing chronic liver diseases”. Chronic viral hepatitis, alcohol consumption, autoimmune diseases as well as non-alcoholic steatohepatitis are from the main causes of liver fibrosis (Lee et al., 2015; Mieli-Vergani et al., 2018). Hepatic stellate cells (HSCs) exist in the sinus space next to the hepatic epithelial cells as well as endothelial cells (Yin et al., 2013). Normally, HSCs are quiescent and mainly participate in fat storage and in the metabolism of vitamin A. HSCs are produced during liver injury and then transformed into myofibroblasts. The activated HSCs resulted in a sequence of events considered as marks fibrosis. The activation of HSCs mostly express alpha smooth muscle actin (α-SMA). Moreover, ECM is synthesized and secreted by HSCs that affects markedly the structure and function of the liver tissue leading to fibrosis (Tsuchi...
It’s all about the spaces between cells: role of extracellular matrix in liver fibrosis
Annals of Translational Medicine
Liver fibrosis is one of the leading complications of a variety of chronic liver disorders, including the nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, liver cirrhosis and liver failure. The progression of liver fibrosis is driven by chronic inflammation, which activates the secretory fibroblasts to the myofibroblast phenotype. These specialized liver cells are called as hepatic stellate cells (HSCs). The excessive extracellular matrix (ECM) secretion creates a large number of complications. Fibrosis is the result of imbalance between the matrix synthesizing and matrix degrading factors. The major ECM proteins include the matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), lysyl oxidases (LOX), lysyl oxidase-like (LOXLs) enzymes, tenascins and others. These ECM proteins present novel avenues for the therapeutics of liver fibrosis. The current review highlights the major role played by these critical matrix proteins in liver fibrosis. Further, some of the targeted formulations used against these proteins are discussed and suggestions are provided to select the course of research for successful clinical translation of basic research findings for the amelioration of liver fibrosis.
Scientific Reports
Liver fibrosis is characterised by a dense and highly cross-linked extracellular matrix (ECM) which promotes progression of diseases such as hepatocellular carcinoma. The fibrotic microenvironment is characterised by an increased stiffness, with rigidity associated with disease progression. External stiffness is known to promote hepatic stellate cell (HSC) activation through mechanotransduction, leading to increased secretion of ECM components. HSCs are key effector cells which maintain the composition of the ECM in health and disease, not only by regulating secretion of ECM proteins such as collagen, but also ECM-degrading enzymes called matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Uninhibited MMPs degrade ECM proteins to reduce external rigidity. Using fibronectin-coated polyacrylamide gels to alter substrate rigidity without altering ligand density, we show that fibrotic rigidities downregulate MMP-9 expression and secretion, and also upregulate secretion of TIMP-1, though not its expression. Using tissue immunofluorescence studies, we also report that the expression of MMP-9 is significantly decreased in activated HSCs in fibrotic tissues associated with hepatocellular carcinoma. This suggests the presence of a mechanical network that allows HSCs to maintain a fibrotic ECM, with external rigidity providing feedback which affects MMP-9 and TIMP-1 secretion, which may become dysregulated in fibrosis. Liver fibrosis in hepatocellular carcinoma (HCC) is characterised by a remarkable extracellular matrix (ECM) stiffness, with extensive deposition and cross-linking of extracellular proteins, including fibrillar and basement membrane collagens. These proteins are primarily secreted by activated hepatic stellate cells (HSCs), myofibroblast-like cells that remodel the extracellular matrix and drive fibrosis in a disease state 1,2. In healthy liver tissue, hepatic stellate cells reside in a quiescent state with cytoplasmic vitamin A-rich droplets, a low number of mitochondria, and a distinct rough endoplasmic reticulum. Following liver injury, HSCs become activated, and in addition to increased production of collagen and other ECM proteins, lose their vitamin A-rich droplets and become increasingly contractile and proliferative. Activated HSCs are also associated with increased inflammatory signalling and altered matrix degradation, all of which can contribute to perpetuation of fibrosis 3,4. HSCs have a key role in remodelling and maintaining the ECM, and achieve this through secretion of ECM proteins such as collagen, as well as ECM-degrading enzymes known as matrix metalloproteinases (MMPs). MMPs are calcium-dependent zinc-containing peptidases and are responsible for the degradation and turnover of most components in the ECM, including collagen 5. Quiescent HSCs maintain ECM homeostasis by balancing the extracellular proteolytic activity of MMPs with the production of ECM proteins, but when HSCs are activated in disease or following injury, excess collagen production and altered matrix degradation leads to a stiff fibrotic state 6. In fibrosis resolution, increased activity of MMPs leads to collagen degradation and ECM softening, with consequent reversion of activated HSCs to their quiescent phenotype. Conversely, perpetuation of the
Genesis of hepatic fibrosis and its biochemical markers
Scandinavian Journal of Clinical …, 2008
Liver fibrosis is characterized by an abnormal hepatic accumulation of extracellular matrix (ECM) that results from both increased deposition and reduced degradation of collagen fibres. Fibrotic liver injury results in activation of the hepatic stellate cell (HSC). Surrogate markers are gradually being substituted for biomarkers that reflect the complex balance between synthesis and degradation of the extracellular matrix. Once the hepatic stellate cell is activated, the preceding matrix changes and recurrent injurious stimuli will perpetuate the activated state. The ECM directs cellular differentiation, migration, proliferation and fibrogenic activation or deactivation. The metabolism of the extracellular matrix is closely regulated by matrix metalloproteinases (MMP) and their specific tissue inhibitors (TIMP). Although liver biopsy combined with connective tissue stains has been a mainstay of diagnosis, there is a need for less invasive methods. These diagnostic markers should be considered in combination with liver function tests, ultrasonography and clinical manifestations.
Digestive Diseases and Sciences, 2011
Background and Aims-Matrix metalloproteinase-2 (MMP-2), a type IV collagenase secreted by activated hepatic stellate cells (HSCs), is upregulated in chronic liver disease and is considered a profibrotic mediator due to its proliferative effect on cultured HSCs and ability to degrade normal liver matrix. Although associative studies and cell culture findings suggest that MMP-2 promotes hepatic fibrogenesis, no in vivo model has definitively established a pathologic role for MMP-2 in the development and progression of liver fibrosis. We therefore examined the impact of MMP-2 deficiency on liver fibrosis development during chronic CCl 4 liver injury and explored the effect of MMP-2 deficiency and overexpression on collagen I expression.
Cooperation of Liver Cells in the Process of Liver Fibrosis
Advances in Anatomy Embryology and Cell Biology, 2001
Fibrosis is the common response to chronic liver injury from various origins including metabolic diseases, viral infections, alcohol abuse, and various chemicals. Liver fibrosis is characterized by both quantitative and qualitative changes in the composition and distribution of extracellular matrix (ECM) that are reflected by a three-to fivefold net increase of ECM and replacement of low-density basement membranelike material by interstitial type matrix abundant in fibril-forming collagens {Friedman 1993; Gressner 1998). This gross remodeling of ECM in the fibrotic liver represents an imbalance between the deposition and degradation of ECM molecules. Hepatic stellate cells, which are involved in the regulation of ECM production and degradation (Table 10), have been found to play a pivotal role in the initiation and progression of hepatic fibrosis (Friedman 1993, 2000; Gressner 1998). Following acute or chronic liver injury, hepatic stellate cells transdifferentiate: they proliferate, lose lipid droplets, change morphology from the star-shaped cells to that of myofibroblasts with the expression of smooth muscle a-actin (reviewed by Gressner 1998), and migrate to sites of tissue damage (Ikeda et al. 1999; Marra et al. 1998b). Activation of stellate cells that initiates the development of the inflammatory process results from multiple interactions between many cell types (injured hepatocytes, Kupffer cells, endothelial cells, platelets, infiltrating inflammatory cells) mediated by cytokines and reactive oxygen species, and from the changes in the composition of the perisinusoidal matrix (Arthur 2000; Gressner 1998). In the case of chronic liver damage, HSC activation persists during the "perpetuation phase" (Friedman 1993; Gressner 1998), and progressive accumulation of ECM leads to liver fibrosis, and finally to cirrhosis. The key role of hepatic stellate cells in the development of liver fibrosis may be deduced from the correlation between the number of HSC and the extent of liver fibrosis observed both in experimental liver injury (Friedman 1993) or in patients with chronic hepatitis C treated with interferon (Sakaida et al.1999). 14.1 Factors Involved in the Activation of Hepatic Stellate Cells Fibrogenesis is regarded as a dynamic process related to the extent and duration of parenchymal cell injury. The cascade of events that leads in vivo to the development of liver fibrosis is initiated by noxious agents that may be different in various kinds of liver damage.lt is, however, widely believed that injury to hepatocytes and/or Kupffer and endothelial cells results in the release of many substances that cause transformation of quiescent stellate cells into myofibroblast-like cells. The activation ofHSC may 97
Liver International, 2010
Background: During fibrogenesis in the liver, in which excessive remodelling of the extracellular matrix (ECM) occurs, both the quantity of type III collagen (CO3) and levels of matrix metalloproteinases (MMPs), including MMP-9, increase significantly. MMPs play major roles in ECM remodelling, via their activity in the proteolytic degradation of extracellular macromolecules such as collagens, resulting in the generation of specific cleavage fragments. These neo-epitopes may be used as markers of fibrosis. Aims: The current study investigated whether a novel enzyme-linked immunosorbent assay (ELISA) assay specifically measuring an MMP-9-cleaved sequence of type III collagen located at position 610 (CO3-610C) may be used as a marker of liver fibrosis. Material and methods: Bile duct ligation (BDL) was performed in 20 rats, with sham operations performed on another 20 rats. Serum levels of the neoepitope CO3-610C (MMP-mediated type III collagen degradation) were determined with an ELISA at 14 and 28 days post-surgery. Liver fibrosis was evaluated by quantitative digital image analysis of Sirius red-stained formalinfixed and paraffin-embedded sections. Western blot and densitometry were performed to confirm the CO3-610C ELISA data. Results: CO3-610C levels in serum increased significantly in BDL rats compared with those undergoing sham operations (% increase: 14 days = 153%, P o 0.0001; 28 days = 134%, P = 0.0014). This increase was confirmed by Western blot and densitometry of the identified bands. The CO3-610C levels correlated to liver fibrosis (R 2 = 0.23 and P = 0.01), as evaluated by quantitative digital histology. Discussion and conclusion: The data suggest that MMP-9-mediated CO3 turnover is a central event in the pathogenesis of fibrosis, and that the neo-epitope generated may be a novel biochemical marker.